Lymphomatoid papulosis (LP) is a rare skin disease that has a benign clinical course but malignant histopathologic appearance. It has been reported to be associated with Hodgkin's disease both clinically and immunologically. Development of cutaneous T-cell lymphomas and systemic lymphomas has also been reported in LP patients. Therefore, LP has the potential to be a model from which to understand the histogenesis of Hodgkin's disease as well as lymphoma progression. The proposed study involves an epidemiologic approach to test two hypotheses: 1. A viral infection and immune deficiency are risk factors for LP, and 2. LP is a premalignant disease. Three projects are proposed to achieve the above goal: I. To establish a case-registry of LP at the Beth Israel Hospital in Boston to identify and recruit such patients for further study through: 1. advertising in journals and meetings; 2. setting specific criteria for admitting cases to the registry, and 3. creating a data base for LP patients whose information will be readily retrievable. II. To ascertain the association between viral infections and an abnormal immune state and the occurrence of LP through a case- control study. Cases will be recruited from the registry, and matched controls from among friends, classmates, and colleagues of the cases. A standard questionnaire will be administered by an interviewer through telephone to solicit information of occurence of the following diseases in the study subjects and their family and relatives: 1. skin diseases, 2. autoimmune and immune deficiency diseases, 3. allergic reactions to drugs, foods, pollen, etc., 4. infectious disease, and 5. malignancies. Occurrences of these events will be compared between cases and controls. III. To determine the relationship between LP and lymphomas through a follow-up study by: 1. comparing the occurrence of lymphomas between cases of LP and their controls and thus, estimating the relative risk of lymphomas associated with LP, 2. comparing the demographic, epidemiologic, and immunologic characteristics between those cases of LP that develop lymphomas ad those that do not after the same period of follow- up, and 3. in those cases that develop lymphomas, comparing the immunophenotypes of the malignant cells with those of the original LP cells.